<?php

if( is_user_logged_in() ) :
  
  //logged in, get the logged-in template
  locate_template('logged-in.php', true, true); //and that's how we do it!
  
  
else:
  
  //not logged in, get the not-logged-in template. duh.
  locate_template('not-logged-in.php', true, true);
  
  
endif;

?>